Friday, April 2, 2010

“Polar” Sea and Land Surface Temperatures (Not Anomalies)

’ve moved to WordPress.This post can now be found at “Polar” Sea and Land Surface Temperatures (Not Anomalies)
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This post illustrates Arctic and Antarctic/Southern Ocean surface temperatures (not anomalies) using NCDC OI.v2 Sea Surface Temperature (SST) and CPC GHCN/CAMS t2m Land Surface Temperature (LST) data. The intent is simply to show the ranges of the annual variations in temperature and the relative magnitude of those temperature ranges in comparison graphs. In other words, these are reference graphs. I have not provided a detailed narrative for them.

The OI.v2 SST data begins in November 1981. The GHCN/CAMS t2m data is available as far back as January 1948, but I’ve started in January 1979 so that the comparison graphs of LST and SST have similar periods.

Polar is in quotes in the title because these datasets do not include areas with sea ice. Sea surface temperature does not measure sea ice temperature. And like other datasets the GHCN/CAMS t2m data only measures temperature on land—not sea ice. Refer to Figure 1. So there is a “gap” in the data presented in this post; keep that in mind. Figure 1 also shows complete land surface temperature coverage for the Antarctic. You’ll have to refer to Fan and Dool (2007) “A global monthly land surface air temperature analysis for 1948-present” for the methods used to infill data. Link to Fan and Dool (2007):ftp://ftp.cpc.ncep.noaa.gov/wd51yf/GHCN_CAMS/cpc_globalT.pdfhttp://i41.tinypic.com/x41xch.png
Figure 1

Note: I’ve used the latitudes North of 65N for the Arctic and South of 60S for the Antarctic and the Southern Ocean.

BobThis is OT to your post, but obviously I have no other way of contacting you. Increasingly ashamed of my intellectual laziness, I recently decided to do some of my own work instead of leaving all the hard graft up to you. I thought I would begin by replicating your comparison of NODC OHC for the major basins (http://i50.tinypic.com/2eexa8w.png) as a learning exercise.I downloaded and extracted the 3 month TAR file direct from NODC (I went to http://www.nodc.noaa.gov/cgi-bin/OC5/3M_HEAT/heatdata.pl?time_type=3month700) as there’s a note on the KNMI page saying ‘please consider getting this from the source’ or words to that effect.I am now the baffled custodian of 220 DAT files. I can import them into Excel (I opened one to be sure) but the embarrassing truth is I have no idea how to deal with the raw data.First, should I be using Climate Explorer to sort out this mass of apparently undifferentiated temperature measurements into ocean basins, and if so, how?If not, what is the proper procedure for importing the files into Excel (delimited? etc) and then sorting them out into individual basins?Something tells me I am taking a bit of a risk asking all this. If time constraints do not permit discussions of this type, fair enough. You aren’t getting paid to hold hands. But if you can take 10 minutes to explain to a novice how to proceed, I would be extremely grateful. Alternatively, what about a tutorial post (I have looked on your site but did not find one)? Then if anyone else asks for help, you can just point them at it and job done. Once I get going, hopefully I will be able to continue on my own. I just want to see for myself for once.I am happy to provide my email address if you would like it.Best regardsDominic

Dominic: The "note on the KNMI page saying ‘please consider getting this from the source’ or words to that effect" appears on many of the pages for the datasets. For most of us that's not an option, because unless you're familiar with a programming language and are intimate with the formatting of the dataset, there's nothing you (or I) can do with the raw data. That's why there's Climate Explorer. KNMI has already downloaded the data from the source, and that’s what’s available through Climate Explorer.

You asked, “First, should I be using Climate Explorer to sort out this mass of apparently undifferentiated temperature measurements into ocean basins, and if so, how?”

No. As noted above, they’ve already got the data on their computer and you use their computer to sort the data that resides there.

You asked, “If not, what is the proper procedure for importing the files into Excel (delimited? etc) and then sorting them out into individual basins?”

Start again on the “Climate Explorer” webpage:http://climexp.knmi.nl/selectfield_obs.cgi?someone@somewhere

Select the dataset you want and press enter. On the next page is where you enter the coordinates for the desired subset. Then press enter. That’ll bring you to the “Time Series” page. Anomalies are the third graph. There’s a group of links just above it. Click on “Raw Data”. That page presents the data in two columns for import to a spreadsheet: numerical month and the data values for those months. You will have to isolate the “numerical months” from the “data” (converting it to a table in MS Word works) before copying and pasting to EXCEL.

BobMany thanks for this.I am embarrassed to say I have just found your instructions in the Data Source section of your post on NODC OHC vs GISS projections (Fri Oct 16 2009). My apologies for not having looked properly first. Your patience and help are much appreciated.Dominic

John: You asked, "...do you envision this Nino will lead to a bump in polar anomalies?"

The lag is about a year, if memory serves me well, between an El Nino and an Arctic response.

You asked, "Any thoughts on whether it will just be a maintenance bump like recent Ninos or an actual step-bump like the 98 Nino?"

I'm "hoping" for a step with this El Nino (without any volcano noise) so that the effect will be easy to see; that is, two steps in succession after the 1997/98 and 2009/10 El Nino events.

You asked, "Would we see any evidence of the bump yet in an updated version of those pictures?"

Still a little early for a step in the TLT anomalies of the mid-to-high latitudes of the Northern Hemisphere. The El Nino peak was only three months ago. It'll take a few months more for the El Nino to end and another six months for the La Nina to appear, assuming we're going to have a La Nina. Not every El Nino is followed by a La Nina. The step would start to show itself during the La Nina, if it's going to show up at all. (The AMO peaked in 2005 and I'm not sure much how it helped the apparent shift after the 1997/98 El Nino.)

Comment Policy, SST Posts, and Notes

Comments that are political in nature or that have nothing to do with the post will be deleted.####The Smith and Reynolds SST Posts DOES NOT LIST ALL SST POSTS. I stopped using ERSST.v2 data for SST when NOAA deleted it from NOMADS early in 2009.

Please use the search feature in the upper left-hand corner of the page for posts on specific subjects.####NOTE: I’ve discovered that some of the links to older posts provide blank pages. While it’s possible to access that post by scrolling through the history, that’s time consuming. There’s a quick fix for the problem, so if you run into an absent post, please advise me. Thanks.####If you use the graphs, please cite or link to the address of the blog post or this website.